There is a long history of impromptu performance and installation art on public transportation. Last month some friends of mine and I decided to make a train on San Francisco's BART system into an art gallery during rush hour on a Friday.

There are some important things to keep in mind when conducting flash mob type projects. First, you don't want any of the effects to be permanent or damaging. The point is to brighten people's day not to inconvenience them. Along those lines, the second thing to keep in mind is easy installation and removal. Just like hiking, this should be a leave-no-trace sort of experience. The third important aspect is timing and location. Make sure you choose a time and a place where there are enough people to appreciate the work but not so many that it becomes an annoyance.

Step 1: Create an Arts Collective

Pop Up Underground is an arts collective for tactical urbanism, and place-based installations. We aim to inspire whimsy, curiosity and smiles in the midst of the city. Projects range from commissioned public sculptures, to helpful subway gadgets.

Step 2: Write an RFP

A request for proposals (RFP) is a document outlining the scope of a project, grant, gallery show or sponsorship. A good RFP introduces the organization, briefly explains the project, and provides details about deadlines and constraints for submissions.

The RFP we wrote for the BART Gallery is attached above.

Step 3: Collect and Frame Work

We distributed the RFP among friends in the art world as well as on a number of blogs and forums about art in the Bay Area. Within days proposals started flooding our inboxes from all over the world. We were blown away by the enthusiasm among artist and the quality of work submitted.

We accepted both physical and digital copies of work, so printing and framing of work became a major task.

Step 4: Add Suction Cups

In order to actually hang the work on the train we decided that the best option would be to use suction cups and stick the work to the windows.

Adding the suction cups was simply a matter of drilling a small hole in the frame and using a small drop of epoxy to adhere the suction cup.

If you are using this method make sure the suction cups you buy are good quality. Cheap suction cups will probably not hold the weight of the frame for very long.

Step 5: Hire a Musician

What's a good gallery opening without a cellist? Luckily the Pop Up Underground team has extremely talented friends who are wiling to help out with projects. Gordon is a professional cellist who was willing to donate some of his time to entertain the guests at our gallery opening on BART.

Step 6: Hang the Show

With all the prep work done, hanging the show was the easy part. We came prepared with all the work, a hanging layout and labels for each piece on static cling film. We got on the train at the first station in the line and had most of the show up before reaching the second stop.

Step 7: Travel in Style

By far the most fun part of the project was watching and listening to the reactions of the BART riders as they discussed the work with one another.

Step 8: Some Favorites

Over all, the team was thrilled by the amazing quality of submissions we got. We got submissions from all types of artist from all of the world but I want I want to highlight a few particularly great pieces.

First, our absolute favorite was a portrait of Rosa Parks painted by a team middle school students from the Leslie H. Walton Middle School. It is absolutely phenomenal and fits so well with the public transit theme we were trying to go for. Huge high five to Yax, Trey and Kolby for doing such great work.

Cartoonist Matthew Kramer from the cartoon blog Cant Take Me Anywhere sent us a few very nice pieces drawn on a train. Matt's minimalist drawing style rocks, and we can't get enough of it.

Photographer Evan Davis sent some rad photos from trains. Above is "The Only Photo I Took in New York".

Dax Opus an artist from Brooklyn sent us some reproductions of his amazing works of pigment on clay. His work is not related to public transit but we his work anyway.

Bay Area based artist Iris Gottlieb sent us a piece called "The Preferences of Pidgins". We liked this piece for the subtle but hilariously witty humor found in much of Iris's work.

Our final favorite is a piece caled #0000FF. It was done by a pointillist robot named George Seur-Bot. Really, we can't get over how rad that robot is.

Step 9: Leave No Trace

We decided it was important to take all of the work with us for a few reasons. First, it's priceless art and you can't just leave work like that lying around for the taking. Secondly, it is tradition in flash mobs to spontaneously start from nothing and leave without a trace.

Step 10: Future Plans

In the next iteration of this project we intend on offering refreshments to the train riders. Obviously, since eating on BART is prohibited, the refreshments would need to be individually wrapped and riders would be asked to wait to open them until they get off. It would also be fun to print out stickers or pins for the guests so they can feel like more welcome in the gallery space.